1. Field of the Invention
The present invention relates to a waveform observing jig and a waveform observing device, which are used for observing a waveform of a signal by an IC tester or the like.
2. Description of the Related Art
A waveform of a signal is tested by an IC tester or the like. A waveform observation or the like, for a timing calibration of a waveform signal is carried out. When such a waveform observation or the like is carried out, a board to be observed is used. A waveform observing jig 100 shown in FIG. 3 is used for observing a signal outputted from the board to be observed.
The waveform observing jig 100 shown in FIG. 3 comprises a contact 10 for a signal, a contact 20 for a ground (GND), a conductive block 40, an insulator 50 and a voltage probe 30. An oscilloscope 60 observes a waveform of a signal outputted from a board 1 to be observed through the waveform observing jig 100.
One contact 10 for a signal and one contact 20 for a GND are attached to the waveform observing jig 100 in order to observe a signal outputted from the board 1 to be observed. An end portion 10a of the contact 10 for a signal is in contact with a gold-plated pad 3 for a signal, to be measured, which is mounted on the board 1 to be observed. An end portion 20a of the contact 20 for a GND is in contact with a GND pattern 2 of the board 1 to be observed. By fetching a signal, the waveform observation is carried out by the oscilloscope 60.
The contact 10 for a signal is held by the insulator 50 provided in the conductive block 40. The contact 10 is insulated from the conductive block 40 by the insulator 50. The contact 10 for a signal is biased toward a lower direction in the figure by a spring or the like, which is not shown. When the end portion 10a of the contact 10 for a signal is in contact with the gold-plated pad 3 for a signal, the other end portion 10b of the contact 10 for a signal is in contact with an end portion 30a of the voltage probe 30.
The contact 20 for a GND is arranged on the conductive block 40 at a predetermined interval from the contact 10 for a signal so as to be in contact with the GND pattern 2 even when the contact 10 for a signal is in contact with any gold-plated pad 3.
A plurality of gold-plated pads 3-1, 3-2, . . . , 3-n for a signal are arranged on the board 1 to be observed, so as to fetch a signal outputted from each electrode of an IC to be measured, where n is a natural number and a plurality of gold-plated pads are inclusively represented by gold-plated pads 3 for a signal. The arrangement of the gold-plated pads 3 for a signal is determined on the basis of an arrangement of lead pitches of an IC to be measured. That is, because each gold-plated pad 3 for a signal is arranged according to the lead pitches of an IC to be measured, each signal outputted from the lead pitches of an IC is outputted to the corresponding gold-plated pads 3 for a signal.
The distance from each gold-plated pad 3 for a signal to the GND pattern 2 differs according to the position of a gold-plated pad 3. Therefore, on the waveform observing jig 100, the contact 10 for a signal and the contact 20 for a GND are arranged so as to adjust their positions to a distance between the GND pattern 2 and the gold-plated pad 3 which is disposed the most apart from the GND pattern 2.
FIG. 4A shows a state in which the contact 10 for a signal is in contact with the gold-plated pad 3-1 for a signal. In FIG. 4A, when the contact 10 for a signal is in contact with the gold-plated pad 3-1 for a signal, to be measured, the contact 20 for a GND is in contact with a point 2-1 on the GND pattern 2. The point 2-1 is a reference point of the GND. Then, a signal outputted from the gold-plated pad 3-1 for a signal, that is, a signal outputted from a lead pitch of an IC, which corresponds to the gold-plated pad 3-1 for a signal, is measured.
FIG. 4B shows a state in which the contact 10 for a signal is in contact with the gold-plated pad 3-4 for a signal. In FIG. 4B, when the contact 10 for a signal is in contact with the gold-plated pad 3-4 for a signal, to be measured, the contact 20 for a GND is in contact with a point 2-4 on the GND pattern 2. The point 2-4 is a reference point of the GND. Then, a signal outputted from the gold-plated pad 3-4 for a signal, that is, a signal outputted from a lead pitch of an IC, which corresponds to the gold-plated pad 3-4 for a signal, is measured.
However, in the waveform observing jig 100 according to an earlier development, as shown in FIGS. 4A and 4B, when the contact 10 for a signal is in contact with every gold-plated pad 3 during the waveform observation, the contact 20 for a GND, which is disposed apart from the contact 10 for a signal at a constant distance, is in contact with the GND pattern 2 in order to set the reference point of the GND. Therefore, the inductance of the GND depends on the position of the gold-plated pad 3 for a signal, to be measured. As a result, there is some possibility that the inductance of the GND becomes large. The waveform of the observed signal is deteriorated. The timing error of the observed signal is caused.
Because the arrangement of the lead pitches differs according to the type of an IC to be measured, it is necessary that a board 1 to be observed, which has a different arrangement of the gold-plated pads 3 for a signal, should be prepared for every type of an IC.
Further, because it is necessary that the contact 10 for a signal and the contact 20 for a GND, of the waveform observing jig 100 should be arranged so as to adjust their positions to a distance between the GND pattern 2 and the gold-plated pad 3 which is disposed the most apart from the GND pattern 2, the waveform observing jig 100 which is suitable for the board 1 to be observed must be used. That is, it is necessary that the waveform observing jig 100 should be prepared according to the type of an IC to be measured.
In order to solve the above-described problems, an object of the present invention is to provide a waveform observing jig and a waveform observing device which can minimize the inductance of the GND in the board to be observed during the waveform observation, and can be adapted to various types of boards to be measured.
That is, in accordance with one aspect of the present invention, a waveform observing jig (for example, waveform observing jig 200, as shown in FIG. 1) for observing a waveform of a signal outputted from a predetermined signal terminal, comprises:
a contact for a signal (for example, contact 10 for a signal, as shown in FIG. 1), for contacting with a signal terminal (for example, gold-plated pad 3 for a signal, as shown in FIG. 1) of a board to be observed (for example, board 1 to be observed, as shown in FIG. 1), and
a plurality of contacts for a ground (for example, contacts 20 for a GND, as shown in FIG. 1), for contacting with a ground pattern (for example, GND pattern 2, as shown in FIG. 1) of the board to be observed,
wherein at least one contact for a ground is in contact with the ground pattern of the board to be observed when the contact for a signal is in contact with a predetermined signal terminal of the board to be observed.
According to the present invention, because the waveform observing jig comprises a plurality of contacts for a ground, when the contact for a signal is in contact with the predetermined signal terminal of the board to be observed, it is possible to observe a signal from the predetermined signal terminal by using a contact for a ground as a reference, which is the nearest to the contact for a signal in the contacts for a ground, connecting with the ground pattern of the board to be observed, that is, by using a contact for a ground as a reference, by which the inductance of the ground is minimized.
Therefore, it is possible to prevent the deterioration of the waveform of the observed signal and the time delay of the signal waveform. One waveform observing jig can be also used for a board to be observed, which has a different positional relationship between the signal terminal and the ground pattern, that is, a different type of board to be observed.
The plurality of contacts for a ground may be attached to one conductive object (for example, conductive block 40, as shown in FIG. 1).
According to the present invention, the plurality of contacts for a ground necessarily have the same electric potential because the contacts for a ground are attached to one conductive object. Because the waveform observing jig has the above structure, the contact for a ground, by which the inductance of the ground is minimized, necessarily becomes the reference of the ground.
The contact for a signal and the plurality of contacts for a ground may be arranged in a straight line.
According to the present invention, one waveform observing jig can be easily adapted to the boards to be observed, which have various sizes.
In accordance with another aspect of the present invention, a waveform observing jig for observing a waveform of a signal outputted from a-predetermined signal terminal, comprises:
a contact for a signal (for example, contact 10 for a signal, as shown in FIG. 1), for contacting with a signal terminal (for example, gold-plated pad 3 for a signal, as shown in FIG. 1) of a board to be observed (for example, board 1 to be observed, as shown in FIG. 1),
a contact for a ground (for example, contact 20 for a GND, as shown in FIG. 1), for contacting with a ground pattern (for example, GND pattern 2, as shown in FIG. 1) of the board to be observed, and
a plurality of attachment portions for attaching the contact for a ground detachably in a position in which the contact for a ground is in contact with the ground pattern.
According to the present invention, because the waveform observing jig comprises a plurality of attachment portions for attaching the contact for a ground, the contact for a ground can be attached to the attachment portion so as to minimize the inductance of the ground in all the attachment portions when the contact for a signal is in contact with the predetermined signal terminal of the board to be observed. As a result, a signal from the predetermined signal terminal can be observed by using the attached contact for a ground as a reference.
That is, it is possible to minimize the inductance of the ground in the board to be observed, and to prevent the deterioration of the waveform of the observed signal and the time delay of the signal waveform. One waveform observing jig can be also used for a board to be observed, which has a different positional relationship between the signal terminal and the ground pattern, that is, a different type of board to be observed.
When the contact for a signal is in contact with the signal terminal, the contact for a ground is attached to the attachment portion so as to minimize the inductance of the ground. Because the contact for a ground can be attached to every attachment portion, the waveform observation is satisfied with one contact for a ground. Further, because the contact for a ground is detachably attached to the attachment portion, the repair of the contact for a ground, the replacement thereof or the like can be easily carried out when the contact for a ground is damaged or the like.
In accordance with another aspect of the present invention, a waveform observing device comprises:
a waveform observing jig comprising a contact for a signal, for contacting with a signal terminal of a board to be observed, and a plurality of contacts for a ground, for contacting with a ground pattern of the board to be observed, wherein at least one contact for a ground is in contact with the ground pattern of the board to be observed when the contact for a signal is in contact with a predetermined signal terminal of the board to be observed,
wherein a waveform of a signal outputted from the signal terminal of the board to be observed, through the waveform observing jig is observed.
According to the present invention, because the waveform observing jig comprises a plurality of contacts for a ground, it is possible to minimize the inductance of the ground in the board to be observed. Further, one waveform observing jig can be also used for a board to be observed, which has a different positional relationship between the signal terminal and the ground pattern, that is, a different type of board to be observed. Therefore, the waveform observing device can observe the waveform which is hardly deteriorated and is hardly time-delayed. Even when the waveform observation is carried out by using a different type of board to be observed, it is possible to carry out the waveform observation by using one waveform observing jig.
The plurality of contacts for a ground may be attached to one conductive object. The contact for a signal and the plurality of contacts for a ground may be arranged in a straight line.
In accordance with another aspect of the present invention, a waveform observing device comprises:
a waveform observing jig comprising a contact for a signal, for contacting with a signal terminal of a board to be observed, a plurality of contacts for a ground, for contacting with a ground pattern of the board to be observed, and a plurality of attachment portions for attaching the contacts for a ground detachably in a position in which the contact for a ground is in contact with the ground pattern,
wherein a waveform of a signal outputted from the signal terminal of the board to be observed, through the waveform observing jig is observed.